Segregated structure of ring polymer melts near the surface: Molecular dynamics simulation study

TL;DR

This study uses molecular dynamics simulations to compare the structural properties of ring and linear polymer melts near surfaces, revealing unique segregation behaviors of ring polymers due to topological constraints.

Contribution

It demonstrates that ring polymers exhibit highly segregated conformations near surfaces, contrasting with linear polymers, due to topological excluded volume effects.

Findings

Ring polymers show highly segregated conformations near surfaces.

The Silberberg hypothesis applies to linear but not ring polymers.

Structural differences include size, adsorption, and coordination number.

Abstract

We study structural properties of a ring polymeric melt confined in a film in comparison to a linear counterpart using molecular dynamics simulations. Local structure orderings of ring and linear polymers in the vicinity of the surface are similar to each other because the length scale of surface-monomer excluded volume interaction is smaller than the size of an ideal blob of the ring. In a long length scale, while the Silberberg hypothesis can be used to provide a physical origin of confined linear polymer results, it no longer holds for a ring polymer case. We also present different structural properties of ring and linear polymers in a melt, including the size of polymers, an adsorbed amount, and the coordination number of a polymer. Our observation reveals that a confined ring in a melt adopts highly segregated conformation due to a topological excluded volume repulsion, which may provide a new perspective to understand the nature of biological processes, such as territorial segregation of chromosomes in eukaryotic nuclei.